Engine sound

Does anyone know what this weird sound is coming from and how to fix it ? It seems to be more quiet when ac is on but not completely quiet.. It started today when i was on a mountain road trip ..M13a engine manual 2002

It comes from the front of the engine near the outside belts of the ac 

Good grief, that’s a good (in a bad way) sound!
No idea as to the source, but a mechanics stethoscope or screw drive placed (carefully) around the engine is a very good way to locate the source.
Alternatively disconnect the AC and Alternator belts and have a feel of any rotating parts. Start and see if noise has gone, if it has it’s going to be something driven by the belts, ie  alternator, water pump / cooling fan / AC unit  / idler bearing

I just found that is the ac compressor and its rattling when rotating.. do i have to change all the ac compressor unit or just the rotator thing for the belt ? 

The AC pulley (rotor?) is made up of two parts,  The outer on which the belt runs and a second part connected to the compressor shaft. Between the two is an electric clutch that connects the two.
AC off then only the outer is rotating with the belt.
AC on then the outer and inner are coupled together, hence the AC shaft turns.

So it you rotate with the AC off, checking that the inner part / shaft is not turning, does it still rattle?

If yes then it sounds like the problem is the electric clutch, aka the pulley. You can take it apart to check for rust or damage. I've seen a few pictures on here of someone doing this, but can't find at the moment.

Think that might have been me Mike. Ive had the clutch assembly apart and cleaned it up. Its an electromagnet with a return spring. On mine the clutch plate rusted solid onto the wheel, making the compressor engaged all the time.

As mike says, check the clutch mechanism operates properly. With a/c switch off it should be stationary in the centre, with it on it should come in/out as required by the a/c demand. If its stuck on all the time then remove the plate you can see by undoing the allen head bolt in the centre of it and prising it off. clean all up and test fit again. Shims may be needed to get clearance to freewheel properly.

A few years ago I heard a loud noise from our drive, it sounded just like a sweet tin full of pebbles being shaken violently. A quick investigation revealed the wife returning home in her 2006 Jimny. “Darling the car is making a bit of a noise, can you look at it please ?”  She uttered. Visions of main bearings, big ends, small ends and pistons work whirled around my head.  It turned out to be the front crankshaft damper/pulley dividing into two parts, the rubber bonding having given up. Luckily a simple job fitting a new one on the car, and I cut a small area of the viscous fan shield away, to make the job easier in the future.